There are many polyfunctional compounds, including diols and aromatic diamines, which are indicated to be useful as chain extenders in the preparation of polyurethane, polyurea, and polyurethane-urea polymers and/or as curing agents for epoxy resins. None of these compounds has a reactivity such as to make it universally ideal, and many fail to provide satisfactory properties in the products made by their use. Thus, there is still a need to find compounds capable of serving as chain extenders or curing agents. U.S. Pat. No. 4,806,616 teaches the use of certain N,N′-dialkylphenylenediamines as chain extenders in preparing polyurethanes and polyureas. In this connection, also see for example U.S. Pat. No. 4,528,363, which teaches the use of secondary aliphatic diamines as part of a resin binder, and U.S. Pat. No. 6,218,480 B1, which discloses use of aromatic diamines as hardeners for polyurethanes. Secondary aromatic diamines have also been used as anti-degradants for rubber; see U.S. Pat. No. 4,900,868.
There is a growing need for chain extenders with slower cure rates, so it would be a further advantage if aromatic diamines exhibited slower curing rates than those of presently available chain extenders.